Aircon Won’t Turn On or Keeps Stopping
Blinking Lights, Short Cycling & What to Check (2026)

Three symptoms, one question

People describe this problem in three ways: the aircon is dead and nothing happens; it starts, runs for a short while and then stops; or it stops and a light on the indoor unit starts blinking. They sound different, but they share one question: is the unit not getting power, or is it getting power and choosing to stop? The first is usually a supply or remote problem you can check yourself. The second means the control board has seen something it does not like and has shut the unit down to protect it.

When nothing happens at all

A completely dead unit is the easiest case, because most of the causes are outside the aircon. Work through them in order:

1. The remote. Put in fresh batteries and point it straight at the indoor unit. If the unit has a manual or emergency button under the front flap, try that: if the unit starts from the button but not the remote, the remote or its receiver is the problem, not the aircon.
2. The isolator. Most split units have an isolator switch near the indoor unit or outside by the compressor. Someone may have switched it off during a service or a repaint.
3. The breaker. Check the distribution board. A breaker that has tripped once in a storm can be reset once. A breaker that trips again when the aircon starts is a fault, not a nuisance.
4. The rest of the house. If other lights and sockets on the same side of the board are also off, the problem is the supply, not the aircon.

Our aircon repair guide covers the wider list of faults; this page stays with the unit that will not start or will not stay on.

It starts, then turns itself off

A unit that starts normally, cools for a while and then stops, sometimes restarting on its own later, is almost always protecting itself. The board watches temperatures and currents, and when something runs too hot or draws too much it cuts the compressor. The usual reasons are ordinary ones:

• A choked filter or a caked coil. With too little air going through, the indoor coil can run too cold or the outdoor side too hot. Clean the filters first; if the coil is dirty, that is a wash, not a repair.
• An outdoor unit with nowhere to breathe. Boxes, plants, a new screen or a neighbour’s wall in front of the fan make it recirculate its own hot air until it trips.
• An outdoor fan that has stopped. If the fan is not spinning while the compressor runs, the compressor overheats and trips out within minutes. That is often the fan’s capacitor or motor.
• A sensor out of place or failing. The board is only as good as what it reads.

Short cycling has one more common cause that is not a fault at all: a unit that is too big for the room cools it quickly, stops, and starts again. Our installation guide explains sizing, and why an oversized unit leaves the room cold but clammy.

When a light is blinking

A blinking timer, power or operation light is not a random glitch. On most units it is the board telling you it has stopped because of a fault it recorded. Some models show a short code on the display instead, or beep a sequence when the unit is switched off and on. The signal is genuinely useful, but only when it is read against the exact model, because the same pattern can mean different things on different model families, even from one brand.

So record it rather than decode it. Before you call anyone, write down:

• Which light blinks, how many times before it pauses, and whether the pattern repeats.
• Any characters on the display.
• The model number on the indoor unit label and the separate one on the outdoor unit.
• Whether the outdoor unit runs at all, and for how long before it stops.
• What changed recently: a power cut, a storm, a service, a new unit next door.

Hand that to the technician instead of a conclusion. Our Sharp and LG repair guide explains why a code table found online for a different model family can send a diagnosis straight to the most expensive part.

Is it safe to reset it?

Once, yes. Switch the unit off at the remote, then at the isolator, wait a few minutes, and switch it back on. If a power cut or a brief storm caused the stop, the unit will usually run normally again. If the same light comes back, or the unit stops again after the same short run, the fault is real and resetting it again only runs a failing part harder.

The cheap fault behind many dead units

The single most common reason an older unit hums but will not start, or starts weakly and trips, is a tired capacitor: the small part that gives the compressor or fan motor its starting push. It is cheap, and testing it takes minutes with the right meter. That matters because a compressor that hums and will not start sounds seized, and a rushed diagnosis can jump straight to a new compressor or a new unit. Our capacitor guide covers the symptoms and the test.

Board, sensor and compressor faults

When the cheap causes are ruled out, the remaining ones need measurement: a sensor reading wrongly, a control board that has failed after a surge, a fan motor, or, least often, the compressor itself. None of these should be named before the unit has been tested. A fair diagnosis tells you which part failed, how it was confirmed, and what it costs to fix, before any part is ordered. Our compressor guide covers the repair-or-replace decision when the compressor really is the problem.

What the fix usually costs

These are the published Klang Valley ranges from our aircon repair and capacitor guides for 2026. The diagnosis comes first; the part is priced once it is confirmed.

Keeping it from happening again

Most protection trips start with airflow. Clean the filters regularly, keep the outdoor unit clear on every side, and have the coils washed when cooling drops rather than after the unit stops. If the unit shares a circuit that also trips with other appliances, or the house wiring is old, have the electrical side looked at too. Our servicing guide covers what a normal service and a chemical wash include.

How ClickBina can help

ClickBina services and repairs aircon across KL and Selangor. WhatsApp us what you see: which light blinks and how, whether the outdoor unit runs, and the model numbers from both units. We reply within the hour, and an aircon diagnostic is RM120–RM400 depending on the unit and the fault. Once the fault is confirmed we give you a flat price for the repair with no hidden charges. For renovation or refurbishment work, a site visit is RM150, waived if you go ahead.

Sources & methodology

• ClickBina aircon repair guide — symptom list and repair price table.
• ClickBina aircon capacitor guide — capacitor symptoms, test order and prices.
• ClickBina Sharp and LG repair guide — why fault signals must be read against the model.

How we estimated prices: every RM figure on this page is quoted unchanged from the ClickBina guides named above. They are typical Klang Valley market ranges for 2026, not fixed rates.